Close-up of an EGR valve

The EGR valve: What is it?

15 July 2019, 11:50

EGR is short for Exhaust Gas Recirculation. This spare part was created in the 1970s in the USA, and its use became widespread in Europe in 1993 in order to meet the updated European standard, the Euro 1.

The EGR valve is a small part located on the motor, but also leading into the exhaust tract. The valve openxs and recirculates the engine's exhaust gas back into the engine cylinders.

EGR valve and pollution reduction

The EGR valve allows for the exhaust gas that is produced by the engine to be sent into the exhaust system for a second time, so it can go through extra combustion. By warming up the gas one more time, the amount of nitrogen oxides (NOx) will be decreased as much as possible.

The purpose of this spare part - which is bothering so many car owners - is therefore to reduce nitrogen oxide emissions produced by the engine that are later released into the air. These molecules are particularly toxic: the WHO had recognized them as one of the main causes of lung cancer.

It is important that the EGR valve matches the latest European standard, which is the Euro 6 norm since 2015. This ensures a sufficient control of the polluting emissions rate. Moreover, the Euro 6 standard limits NOx emissions of the car to 80 mg/km for diesel vehicles – against 500 mg/km for Euro 3 – as stated by EUR-Lex, the EU directive.

This part is mandatory on diesel cars, as NOx emissions are way higher than in gasoline cars.

Clouds over traffic signalling environmental care

The EGR valve and MOT

As there are strict rules for emission levels in the Euro 6 standard, cars that in any way exceed the permitted levels cannot pass the MOT.

Unfortunately, many car owners have started to meddle with the EGR valve - or the diesel particulate filter - to avoid the fairly high cost of a repair. But it is stated by the Department for Transportation that the removal of the EGR valve or particulate filter almost always will fail to be compliant with the road vehicle regulations. This makes it illegal, and the car would not pass the MOT because of its emission levels.

The potential penalties for removing the EGR valve or particulate filter amounts to £1000, but £ 2500 for a light goods vehicle.

Damaged EGR valve – What are the risks?

After a while, soot accumulates in the EGR valve (like in the particle filter). If the valve is not cleaned, it may clog and eventually stay blocked with carbon depostis, which will affect the engine performance.

Indeed, if the EGR valve is clogged, its anti-pollution effect won’t work anymore as the recirculation and second combustion will not happen. This will degrade your driving performances, as you will see a loss of engine power, and there will be more risks for your car to suddenly stall.

In case of a malfunction of the car’s EGR valve, the warning light for emissions in your car’s dashboard will light up.

EGR valve maintenance

Before replacing the EGR valve, you can try to clean it by injecting a special product into the fuel tank. If the cleaning is successful, you can save a lot of money. However, if the soot has been there for a while, cleaning might not be enough.

As an alternative, you can choose to dismantle the valve in order to clean it properly. This option will be more expensive than adding additive, but way more efficient and it could avoid a complete replacement.

What is the price for an EGR valve replacement?

If it is not possible to clean the EGR valve, it is necessary to have it replaced. This job is particularly expensive and it is recommended to compare the prices from different garages, so you can get an idea of what you might have to pay and find a suitable quote.

By using Autobutler to get the EGR valve replaced, other car owners have saved 32 % on average.

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